I just purchased one of Sig's surplus M17s and disassembled it to do a thorough cleaning. I have two P320, so am familiar with the civilian model. But I wasn't able to remove the M17 fire control unit. Is the military version designed to have the FCU not removed by anyone except an armorer?

I cannot speak to what you have or ultimately what was issued but I seem to remember (at least early on) reading that the .MIL pistols would have FCU’s that were not to be serviceable by the average grunt.

The FCU on the military pistols should remove in the same manner as the commercial model. It just may be "stuck" in the grip module by old lubricants and from being "settled" into the frame polymer from shooting.

One of my P320s had a difficult to remove FCU, I just kept working it back and forth and eventually it came loose from the grip.

I believe military models have “tamper resistant” takedown levers and extractor spring pins that require special tools to remove. If, however, the “surplus” M17s don’t have those and the takedown lever has already been removed from the grip module and frame, there should be nothing to prevent removing the FCU in the normal manner.

The SIG Armorer offers a tool to make that easier, and the video on the site shows the problems that can be encountered when removing a tight FCU.

https://www.thesigarmorer.com/...ct/p320-access-tool/

Its been a minute since I took the class but I believe it was just a simple tool same idea as safety hexs and the like. It had two dimples and you needed something with two prongs to move it. I have no idea if thats still current.

Yes, the M17 has an armorer only serviceable FCU.

quote:

Originally posted by Wreckless:
Yes, the M17 has an armorer only serviceable FCU.

What does that mean?
What is different about it other than the tamper-resistant takedown lever? What keeps it in the grip module after the TDL is removed?

The armorer manual I got in October 2018 has the tamper resistant parts removal information, but nothing about a special way of removing the FCU.

IIRC, there is a special tool required to remove the TDL.

It fits into the two holes seen here which keep the TDL in place.

I think there is a similar tool / 2 dots on the back of the slide to keep that from being disassembled, but I can't find a good photo of it.

quote:

Originally posted by RHINOWSO:
It fits into the two holes seen here which keep the TDL in place.

Yes, that is the tamper-resistant TDL. (Thanks for that photo. The armorer manual does not depict it very well.)

But evidently not all the surplus M17 pistols have it.
This is from a screenshot of the SIG Sauer site video about the surplus M17 pistols showing one that was issued. The takedown lever is not the tamper resistant variety that must be removed with a spanner bit (no holes in the end).



In any event, if the TDL is removed, I know of no reason why the FCU cannot be lifted out of the grip module as with other P320s.

Added: I looked at the photos Wreckless posted of his M17 in another thread and it does not have the tamper-resistant TDL. The shot showing the extractor spring pin is out of focus so I can’t be certain, but it appears to be the standard version as well.